1. Field of the Invention
The present invention relates to a multi-domain vertical alignment (MVA) LCD panel, and more particularly, to an MVA LCD panel having a high aperture ratio without suffering from the light leakage problem due to protrusions.
2. Description of the Prior Art
LCDs have been widely applied to various electronic devices, such as mobile phones, personal digital assistants, and notebook computers in recent years. With the rapid development of the large-size flat display market, LCDs have played an important role and have gradually replaced CRT displays. However, conventional LCDs are limited by their narrow view angles. Consequently, MVA LCD panels which can be viewed in wide angles are therefore designed.
Please refer to FIG. 1 and FIG. 2. FIG. 1 is a schematic diagram of a conventional MVA LCD panel 10 while no voltage is applied; FIG. 2 is a schematic diagram of the conventional MVA LCD panel 10 shown in FIG. 1 while a voltage is applied. As shown in FIG. 1, the conventional MVA LCD panel 10 includes a top substrate 12, a bottom substrate 14, a liquid crystal layer 16 filled in between the top substrate 12 and the bottom substrate 14, a color filter layer 18 positioned on the surface of the top substrate 12 facing the bottom substrate 14, a common electrode layer 20 positioned on the bottom surface of the color filter layer 18, a pixel electrode 15 positioned on the surface of the bottom substrate 14 facing the top substrate 12, at least a first protrusion 22 positioned on the bottom surface of the common electrode layer 20, and at least a second protrusion 24 positioned on the surface of the pixel electrode 15. It is noted that FIG. 1 and FIG. 2 illustrate only a single pixel region of the MVA LCD panel 10, and therefore data lines, scan lines, and thin film transistors (TFTs) are omitted for easy illustration.
While a voltage is applied to the pixel electrode 15, liquid crystal molecules are inclined so that light beams passing through the liquid crystal molecules are rotated. The rotated light beams will pass through the color filter layer 18, and therefore viewers can see brilliant colors. As shown in FIG. 2, the liquid crystal molecules are influenced by the first protrusion 22 and the second protrusion 24, and thus are inclined in different directions. This characteristic makes it possible for the conventional MVA LCD panel 10 to be viewed in wide angles.
As shown in FIG. 1, however, the liquid crystal molecules close to the first protrusion 22 and the second protrusion 24 are slightly inclined under the effect of the first protrusion 22 and the second protrusion 24 even when no voltage is applied. This leads to light leakages and color aberrations, and therefore reduces the contrast ratio of the MVA LCD panel 10. For example, when a complete black state for a pixel region is required, the sub pixels red, green, and blue are supposed to be completely dark. As long as light leakages occur, the completely black state cannot be achieved, and this reduces the contrast ratio. Additionally, if a color mixed only by red and green is required in a pixel region, the light leakage of sub pixel blue would cause the color aberration and deteriorate the display effect.
Currently, a black matrix layer is introduced between the top substrate 12 and the first protrusion 22 to solve the aforementioned light leakage problem. However, the black matrix layer solves the light leakage problems at the cost of low aperture ratio, which is not desired.